HEILONGJIANG, Northeast China — At 2:30 p.m. on the dot, 52-year-old Wang Zhanjun rushes to the “nursery” with two bottles of goat’s milk. For 21 years, he has nursed Siberian tiger cubs at a breeding center in Harbin, about 500 kilometers from the Russian border. “It’s time to feed these little guys,” he says, giving the bottle to a fuzzy, sharp-clawed cub in his arms.

Siberian tigers are endangered worldwide. Though the population has recovered a little in recent years, with the subspecies’ status revised from “critically endangered” to “endangered” in 2007, Siberian tigers still suffer from the effects of habitat destruction, poaching, shortage of prey, and inbreeding within their limited gene pool in the wild.

According to state news agency Xinhua, there are currently about 500 wild Siberian tigers in Russia and around 30 in China’s northeast. Controlled breeding in captivity aims to raise strong, healthy tigers that can eventually be reintroduced to the wild to help rebuild the genetic diversity that the subspecies needs to survive independently.

But the “rewilding” process is challenging: Though Chinese breeding centers now house over 1,000 Siberian tigers, after more than 30 years of expert conservation efforts, not one has yet been released into the wild. Now, breeders, trainers, and caretakers like Wang are working toward a tentative date of 2025 for the first round of releases, under a new national strategy for the subspecies.

The Siberian Tiger Park in Harbin is the larger of two breeding centers in China. Wang joined the park when it opened in 1996, 10 years after its smaller predecessor, also in Heilongjiang province. Over the last two decades, he has helped to raise hundreds of tiger cubs abandoned by their inexperienced mothers.

Tigresses often abandon their young, especially their first litter. In the breeding center, the survival rate for cubs is over 80 percent, but in the wild, about 50 percent of tiger cubs die in their first year.

Wang lovingly feeds, massages, and weighs the abandoned cubs, and even helps the young tigers defecate by massaging their rears. “I’m not even this good to my own child,” he tells Sixth Tone at his “office” in the park’s Shed No. 4.

Shed No. 4 is known as the center’s mother and infant ward. It currently houses 10 cubs that Wang looks after, as well as a few pregnant tigresses and four experienced mother tigers who take care of their cubs by themselves.

Once the cubs turn 2 months old, Wang must hand them over to a trainer. When they are 4 months old, they will be grouped with other cubs the same age. That’s when the wilderness training kicks off.

The Harbin center is now home to 600 tigers, with just over half living in the park’s open range area that simulates their natural environment. They roam in groups of 20 to 30, visited by tourists eager to glimpse these young and powerful beasts. “These are the candidates for breeding and releasing in the future,” explains Liu Dan, deputy director of the park.

Tigers that are elderly, ill, or disabled live indoors in individual rooms. They share an outdoor space but won’t be bred or released into the wild.

Though Siberian tigers are endangered, when it comes to breeding, it isn’t simply a matter of “the more, the better.” To ensure the survival of the species, the breeding center limits the number of newborns to around 100 each year and performs exhaustive checks for genetic quality and diversity.

Every year, the center selects around 50 pairs of tigers for mating based on their genes and physiques. DNA tests are performed to guarantee that there has been no inbreeding in the last three generations of each tiger’s pedigree.

Tigers can reproduce between the ages of 4 and 14. Pregnancies last 105 to 110 days and usually produce two to three cubs. Polyandry is common. “We do a paternity test on each cub to prevent inbreeding in the future,” says Liu.

In addition to expanding the population, Liu dreams of releasing the captive tigers back into the forest. “The purpose of breeding is to set them free someday; otherwise, it’s meaningless,” he says. Once the bottle-fed tigers reproduce with wild mates, Liu believes the quality of the gene pool will advance with each generation.

The breeding center has been working on wilderness training since its inception. Visitors can buy live chickens and ducks to toss to the tigers in the open range area, and the trainers also throw them cows and sheep to stimulate their natural hunting instincts. Training also covers resistance against cold, heat, and hunger; running; reproduction; and habitat selection.

In the open range areas, the big cats often fight over the livestock. Tao Guodong has been patrolling in the park for over 20 years; his job is to stop the tigers from fighting by driving them apart with a vehicle covered in protective screening.

“I wish they could fight for food like this in the wild,” Tao says, “but there’s insufficient prey for them in nature right now.”

When the wilderness training first began, Liu says the tigers in the park would not eat anything with fur. Cubs under 2 years old would have to sleep inside when the winter temperatures dropped below minus 30 degrees Celsius. The rocks and soil in the open range area would hurt their paws. “It was just like how children in the countryside can walk barefoot, while city kids don’t have this ability,” Liu says.

Through the trainers’ ongoing efforts, the tigers have made progress with each new generation, but Liu says they’re still limited in their ability to fend for themselves. “The survival conditions in the park differ greatly from the wilderness,” Liu confesses. “We need a larger base in nature reserves and more prey for the tigers in order to conduct more advanced wilderness training.”

In 2016, the State Forestry Administration announced a 10-year plan for the wilderness training and release of Siberian tigers — the first such plan on a national level. They have set 2025 as the potential release date, but there is much to prepare in the meantime.

The first step is to build a national park across Heilongjiang and Jilin provinces, where more advanced wilderness training will take place. The park is scheduled for completion in 2020. Then, Liu and his team will select “individuals of excellence” from their captive population to undergo advanced training.

“Once they can capture prey and reproduce by themselves, they’ll be one step closer to release,” says Liu.

In 2015, the Harbin center started allowing the more experienced tigresses to deliver and take care of their cubs in the open range area. Now, these cubs are healthy 2-year-olds that still live with their mothers in the simulated wilderness within the park. “There’s no labor room or shelter — it’s just like the reality in nature,” Liu says, adding that these tigers will be priority candidates for advanced training in the forthcoming national park.

At the top of the food chain, tigers have a tremendous impact on their ecological environment. Any missing link in the food chain could threaten the tigers’ chances of survival.

In July 2015, the World Wide Fund for Nature and the Forestry Department of Jilin province set up a breeding base for tiger prey — such as red deer and sika deer — at a nature reserve in Jilin to prepare for the “return of the king.”

Advanced wilderness training in the future national park will focus on capturing wild prey. Liu explains that first, trainers will slaughter the prey and chop it into pieces with the fur attached to familiarize tigers with the scent. “It’s a long and complicated process, and it will require tigers of different generations to work together,” Liu adds.

It’s not yet known how many tigers will be released in 2025. Even with successful training and sufficient prey, newly released tigers will face attacks from their wild peers and unknown risks of disease.

Over the past two decades, Wang has cuddled hundreds of tiger cubs in his arms, but he knows that once they leave him and start wilderness training, they will become fierce; he will only be able to watch them from a distance.

“It’s bittersweet for me but good for them,” Wang says. “I hope one day, they can go back to nature where they belong, but I don’t know when that day will come.” Wang himself is due to retire in 2025.

Editor: Qian Jinghua.

(Header image: Siberian tigers stand in the water at the Siberian Tiger Park in Harbin, Heilongjiang province, June 27, 2017. Courtesy of Zhu Yuehan/Siberian Tiger Park)